September 30, 2006

Main Camera on Aging Hubble Shuts Down

BALTIMORE (AP) - The main camera on the Hubble Space Telescope shut down unexpectedly for the second time this year, the operators of the orbiting observatory announced Friday.

The Space Telescope Science Institute, which coordinates use of the telescope, said the camera shut down Saturday. Program managers at NASA's Goddard Space Flight Center in Greenbelt blamed the shutdown on a voltage drop to the device and were investigating the cause and what action to take, but expected to have at least part of the camera working again by Sunday.

In the meantime, observations on the Hubble were being rescheduled to use other instruments, the Baltimore-based institute said.

The Advanced Camera for Surveys, installed by a space shuttle crew in March 2002, increased Hubble's vision 10 times and has given the clearest pictures yet of galaxies forming in the very early universe. The instrument consists of three electronic cameras, filters and dispersers that detect light from the ultraviolet to the near infrared.

The orbiting Hubble telescope, launched in 1990 by the space shuttle, has revolutionized the study of astronomy with striking images of the universe. Using images from the craft, scientists have determined the age of the universe and discovered the mysterious dark force that is causing all of the objects in the universe to move apart at an accelerating rate.

However, a servicing mission by the space shuttle is needed to install two new instruments as well as fresh batteries and gyroscopes to keep the aging telescope working until 2011 or 2012. NASA, which has not decided whether to schedule a servicing mission, is planning to replace the Hubble with a new, improved version, called the James Webb Space Telescope, scheduled for launch in 2011.

NASA scrubbed the servicing mission because of safety concerns following the loss of the shuttle Columbia in 2003. That decision prompted an outcry from scientists and the public and forced NASA to reconsider.

The latest shutdown occurred as operators were switching between two of the three instruments on ACS, said Art Whipple, the Hubble Space Telescope systems manager at Goddard.

A voltage drop on one of the three, the High Resolution Channel, prompted the instrument to automatically shutdown. Operators have narrowed the problem down to an electrical relay on the HRC or the connections to the relay, Whipple said.

The most frequently used instrument on the ACS, the Wide Field Channel, was not believed to have been affected and is expected to be brought back online Sunday evening, Whipple said.

When, or if, the HRC, which accounts for less than 20 percent of the main camera's observations, can be used again is not known, Whipple said.

"We are still investigating what our options are right now," Whipple said. "I'm trying hard not to speculate here, we really are in the early parts of this investigation and the main focus is bringing up the wide field channel."

"That's our real workhorse channel on this instrument and that's been the primary focus over the last few days. We're only now really getting deeply into what our options are for the high resolution channel."

The ACS shut down June 19 after voltage readings exceeded the acceptable range. The instrument came back to life nearly two weeks later after operators switched over to a backup system.

The June power supply problem affected two of the three detectors.

The ACS was developed jointly by Goddard, Johns Hopkins University, Ball Aerospace in Boulder, Colo., and the Space Telescope Science Institute.


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